Electric heating unit



2 Sheets-Sheet 1 original Filed May 28, 1957 hm EN n y 2 R n mw a www w .NNWN m Qd II 5w I C www fk RI NQ ESN n* wd Sw @EN @u Q f Y Sw USN ,QN We# E .NNl Il; l /|\..|W-||| l n.|l|- Q Hx 4 I f www 4% om L )n TE -.....HH........ www: E "x r I ,Sw .www WENEN E QNN %N July 3,1962 l.. c. HANsoN ELECTRIC HEATING UNIT 2 Sheets-Sheet 2 Original Filed May 28, 195'? mwn INVENTOR. Zero HQZSOJZ United States Patent Otitice 3,042,784 Patented July 3, 1962 9 Claims. (Cl. 219-37) This invention relates to tubular sheathed electrical heating units of the type adapted for range surface heating and has reference more particularly to facilities by which the terminals of the tubular sheathed elements thereof are collectively incorporated in and insulated by a protective junction fitting for connection of current supply wires thereto, this application being a division of my copending application Serial No. 662,041 yfiled May 28, 1957, now abandoned.

In such heating units the tubular sheathed elements thereof are usually arranged in the form of a Hat winding which is set in an opening of the range cooking top or in the opening of a mounting ring with the top face of the winding elevated slightly above the surrounding surface so that a cooking utensil will rest directly on the Winding, and it is customary to provide a pan underneath the winding which serves not only to collect spillage but also as a reflector to direct heat upwardly to the bottom of the pan or utensil on the winding. This pan or reflector may be made as a part of the range top or of the mounting ring but generally is a separate part which may be removed for cleaning.

Various expedients have been employed to permit access to the pan and the underside of the heating unit for cleaning thereof, the heating unit being sometimes arranged for complete removal for this purpose, but generally it is preferred to hinge the heating unit at one side of the opening of the range top or ring so that it tilts to an upraised position at one side of the range top or ring opening to permit convenient access for cleaning or removal of the pan and for cleaning the underside of the heating unit itself.

In such heating units the end portions of the tubular sheathed elements of the winding are usually bent downwardly to a suitable level below the plane of the winding and extending outwardly through the side wall of the ring or pan so that they terminate at a protected place underneath the range rtop for connection of current supply conductors to terminal wires which project from the ends of the tubular sheathed elements, and -it is important that the terminal wires and connections thereof with the current supply conductors be protected and insulated from one another and safeguarded against access of spillage or grease thereto as such spillage or grease at the terminal ends may cause current leakage or shorts to occur at the terminals or it may even migrate into the end of the tubular sheath and cause current leakage or shorts therein.

Generally the terminal end portions of such heating units extend outwardly in a -group and are commonly arranged adjacently in spaced apart parallel relation with the sheath ends and projecting terminal wires in generally matching side by side relation, and it is customary to mount on the sheath ends a junction fitting of electrical insulating material, commonly referred to as a terminal block, which is usually of two piece construction, with the terminal wires projecting into the interior -thereof and having the current supply conductors connected to the terminal wires therein.

In accordance with the present invention, the terminal block is a simple one piece body provided at one side thereof with recesses -at the bottom of which the supply Wires are connected to the terminal wires in a readily accessible but adequately protected manner and the block 2 is attached to the sheath ends in a manner in which it is qui-te readily applicable thereto and removed therefrom when the current supply conductors are not connected to the terminals and is safely locked pn the sheath ends when the current supply conductors 'are connected to the terminal wires.

The principal objects of the invention are, to provide an improved heating unit of the type having the terminal end portions thereof extending outwardly in a group as explained above; to provide an improved junction fitting or terminal block of simplified form which may be made at low cost and minimizes the time required for assembly thereof on the terminal end portions of the heating unit and for connection of current supply conductors to the terminal wires of the heating unit; to insure a positive and secure connection of the terminal block to the terminal end portions of the heating unit; to safeguard the exposed connections therein against damage or accidental shorts and against access of spillage from cooking thereto; and to permit convenient access lto and inspection of the electrical connections therein without disassembly of any parts thereof, these and other objects being accomplished as pointed out more particularly hereinafter and as shown in the accompanying drawings, in which:

FIG. 1 is a plan view of a heating unit assembly embodying the features of the invention;

FIG. 2 is a vertical sectional view taken substantially along line 2 2 of FIG. l and illustrating the heating unit in position in the cooking top of an electric stove, and showing in broken lines the up-raised position of the heating unit and in dotted lines the location of the sheath ends which lead from the inner ends of the coils of the winding;

FIG. 3 is a vertica1 sectional view through the terminal block, the view being taken substantially -along the line 3 3 of FIG. l;

FIG. 4 is a fragmentary plan section taken substantially along the line 4 4 of FIG. 2 and showing the hinging means and the yielding detent means;

lFlG. 5 is an enlarged fragmentary vertical sectional view taken substantially along line 5 5 of FIG. 4 and showing the hinge and detent means in the relation that they occupy when the heating element is in its horizontal position of use;

FIG. 6 is a view similar to FIG. 5 showing the hinge and detent means in the relationship that is occupied when the heating element is in its raised or open position;

FIG. 7 is a fragmental portion of FIG. 2 showing the bearing arrangement employed in pivotally mounting the heating element;

FIG. 8 is a fragmentary vertical sectional view taken substantially along the line 8 8 of FIG. l.

FIG. 9 is a fragmentary vertical sectional View taken substantially along line 9 9 of FIG. 8.

FIG. 10 is a. bottom plan view of the central portion of the spider upon which the heating element is carried, and

FIG. 1l is a fragmentary vertical sectional view taken substantially along line 11 11 of FIG. 1.

For purposes of disclosure the invention is illustrated herein as embodied in a heating unit and mounting ring assembly 20 that is adapted to be mounted in an opening 21 in the cooking top 22 of an electric range as indicated in FIG. 2 of the drawings. The assembly 20 comprises a mounting ring 23 having a supporting spider member 24 pivoted or hinged at one edge thereof at 27, and arranged to carry spirally coiled heating unit means 25 that has the terminal ends 26 thereof associated with a terminal block 28, there being a heat reflecting and spillage collecting pan 29 supported in the mounting ring 23 in a position beneath the spider 24 and the heating means 25.

The mounting ring 23 has a generally horizontal annular flange 23H that curves downwardly at its outer edge so that such outer edge may rest upon the cooking top 22 as shown in FIG. 2, and at the inner edge of the horizontal flange 23H, a downwardly extending substantially vertical annular wall 23V is formed, the lower end of which has a narrow inwardly extended horizontal support flange 23'F. The lower supporting llange 23F serves to support the pan 29 which, as shown in FIG. 2, has an angular ange or rim 29H that rests upon the horizontal flange 23F of the mounting ring. The pan 29 is relatively deep, and has a sloping or conical surrounding wall, for reasons explained hereinafter, and, as shown in FIG. 2, an inward embossure 29E is provided at what may be termed the -forward portion of the surrounding wall of pan 29 for finger engagement to facilitate lifting and removal of the pan 29 when this is desired. At its rear side the pan 29 has a clearance opening 29C formed therein, this clearance opening being in the nature of a wide notch that extends to the upper edge of the pan, and provides clearance through which the terminal ends 26 of the heating means 25 may extend, and within which such terminal ends may move when the heating element is pivoted to its elevated position .as indicated by the broken lines in FIG. 2 and as described hereinafter.

The spider 24 is formed from a pair of sheet metalfstrips that have corresponding portions 24W between their ends fastened -together by rivets 31 or in any other convenient manner, and at one end of the portions 24W, the sheet metal members are bent to a diverging relationship to provide forward arms 24F, while at the other or rear end of the portions 24W the sheet metal members are bent in a diverging relationship to provide diverging rear arms 24R. The arms 24F and 24R are of such a length that the ends thereof may be located over the ilange 23H so as to be supported thereon, it being noted however, that such support -is in most instances obtained by resting on the flange 29H of the pan 29 as will be evident in FIG. 2 of the drawings. At their outermost ends, the rear arms 24R of the spider have integral extensions providing connector arms 24C that are bent so as to extend generally toward each other as shown in FIG. 1. At the inner ends ofthe connector arms 24C, the sheetV metal strips are bent into a spaced parallel relationship so as to extend rearwardly and provide hinge arms 24H. The hinge arms 24H provide a portion of the hinge means whereby the spider 24 is pivotally hinged to the mounting ring 23, and in providing this hinged relationship, the hinged arms 24H extend through spaced vertical slots 33 that are formed in the vertical flange 23V of the mounting ring. These slots have their opposite edges offset in opposite directions as shown in FIGS. 4 to 7 to provide opposed arcuate bearing seats 33S to receive and support the ends of .a hinge piu 344 The hinge pin 34 extends at its opposite ends through pivot openings in the hinge arms 24H, and the hinge pin is supported therebeyond in the bearing seats 33S as will be evident in FIGS. 4 to- 7. The arms 24H are cut back at the -top as indicated at 68 to provide clearance permitting the heating unit to be tilted to a highly upraised position.

The spider 24 may thus be pivoted from a horizontal position of use to a raised or open position, and means are provided whereby the spider is yieldingly maintained in its horizontal position or in its generally upright or open position. Such yieldingly retaining means are provided on the outer face of the rear portion of the ange 23V,

as shown particularly in FIGS. 2 and 4 to 6. Thus,

in the portion of the vertical flange 23V that is located between the slots 33 an elongated flat spring 3'5 is mounted so as to extendat its opposite ends into a cooperating relationship with respect to the hinge arms 24H. The spring 35 is held in position by a relatively heavy clamping strip 36 that is disposed on the outer or rear -face of the strip 36 and the spring 35 in position. The plate 36 terminates in spaced relationship with respect to the ends of the flat spring 35, and these projecting ends of the spring 35 are arranged to bear yieldingly against projecting pointed ends 24E of the hinge arms 24H. The pointed ends 24E are provided by angularly related sur- Ifaces 24S, and when the spider 24 is in its horizontal position, the ends of the spring 35 bearkagainst the pointed ends 24E at an elevation above the pivotal axis of the arms 24H, thus to exert yielding forces on the arms 24H tending to maintain the spider 24 in its horizontal position as shown in FIG. 5 of the drawing. When the spider 24 is swung to its upraised position the ends of the spring 35 bear against the pointed ends 24E at an elevation below the pivotal axis of the -arms 24H and thus exert a yielding force to hold the spider in the upraised position as shown in FIG. 6.

Ilhe heating means 25, as illustrated herein, is made up of two elongated sheath type electrical heating elements 25E that are wound in a double flat spiral as will be evident in FIG. l with the coils of the elements 25E intercalated, and in the relatively large central space within the spirals, an eseutcheon plate P is mounted on the spider 24. The plate P has downward edge flanges 38 that -are anchored in slots 38S in the arms 24F and 34K of the spider 24. As shown in FIG. l0, the ilange 38 is slightly bent at 38B at several points to engage the sides of the arms of the spider and thus prevent rotative displacement of the Plate P.

The heating elements expand and contract in the heating and cooling thereof, and because of the spiral form, a slight radial expansion and contraction of the coils occurs, and it is important that the spiral elements be suitably mounted so that they are `free to expand and contract in accordance with temperature changes.

To this end, only the outer coil of each element 25E is attached to the spider 24 and only at places remote from the hinge H and the terminal ends 26. Thus the outer coil of each element 25 is secured to the forward arms 24F only of the spider as shown in FIGS. l and 2.

For this purpose of securing these outer coils to the spider arms 24F, wire fasteners 39 of inverted L-shape are employed having short upper arms 39A substantially paralleling the coils and welded to the underside thereof and having the legs 39B thereof welded near their lower ends to embossments 40 pressed from the spider arms 24F all -as shown particularly in FIGS. 8 and 9.

The coil of the heating unit is fastened to the spider arm in a position in which it rests on the upper edge of the spider arm, and the spider arms 24F are of such flexibility that, although the heating elements 25E are securely attached to the spider 24, such increase and decrease in length of the coil between the two places of fastening thereof 'which occurs on account of temperature changes, is readily accommodated by the flexibility of the arms 24F, and any change in arcuity of the coil portion is accommodated by permissible twist of the wire of the inverted L-shaped wire fasteners 39.

As will be evident in FIG. 1, the heating elements 25E are wound in -a double spiral and at the outer ends of the spirals are bent downwardly -as at 60 and are then bent outwardly at 61 to provide the relatively short terminal portions 26 as shown in FIGS. 1 and 2 and at the inner ends of the spirals the heating elements 25E Iare likewise bent downwardly as at 62 and then outwardly as at 63 to provide the relating long terminal portions 26 as shown in FIG. 1 and by dotted lines in FIG. 2.

'Ihe downwardly extending portions 60 and 62 are so related that the several terminal portions 26 may extend parallel to each other beneath the hinge H and toward the terminal 'block 28, and it is an important feature thereof that the terminal portions 26 are not horizontal in the normal position of the heating unit but slope upwardly from the bends 61 and 63 to the terminal block 28 so that the bottom of the bends 61 and 63 are at the lowest location of any portion of the termin-al ends 26.

The heating elements E are of conventional form, each comprising a tubular metal sheath 64 containing a central helical resistance 65 which is embedded in heat conductive electrical insulating material 66, such as magnesium oxide powder, compacted to a hard dense mass which electrically insulates the resistance from the sheath.

The at winding composed of the spiral portions of the heating elements 25E constitutes the vactive portion of the heating unit and accordingly the resistances 65 of the heating elements 25E, in accordance with conventional practice, extend to or into the downturned portions 60 and 62 where they are electrically connected to low resistance -terminal conductors which extend therefrom out through the bends 61 and 63 and through the terminal portions and project from the sheath ends, as indicated at 25T 'for attachment of current supply conductors thereto. These low resistance terminal conductors are located centrally within the sheaths 64 and embedded, like the resist-ances 65, in compacted insulation 66 which may terminate a suicient distance from the sheath ends to accommodate high temperature resistant plugs 67 of a material, such as silicone rubber, which closely encircle the wires 25T and tit snugly within the sheath ends to seal the latter.

The terminal portions 26 extend an equal distance outwardly under the range top 22 so as to terminate at a place where they are safely protected against spillage from cooking operations on the heating unit, and their outer ends are arranged to extend into pockets of the terminal block 28 in which provision is made vfor connection of current supply wires to the exposed projecting ends 25T of the `terminal conductors.

This terminal block 28 is of ceramic material and is formed with a bottom wall 28B, the upper face of which is stepped as at 68, and hav-ing side walls 28S and intermediate walls 28D extending upwardly from the bottom wall and all extending lforwardly from a relatively thick rear or outer end wall 2ER having openings 45 therethrough.

Between the two intermediate walls 28D and between one of these walls 28D and one of the side wall-s 28S,

two small pockets are formed to accommodate respectively therein terminal clips 41 and 42, and between one of said walls 28D and the other side wall 28S a large pocket is formed to accommodate a large common terminal clip 43 therein, and each of said pockets has one of the openings 45 leading therefrom through the rear or outer end wall 28R. The terminal clips 41 and 4Z are associated respectively with the corresponding long ends 26 of the two heating elements 25E which have the projecting terminal wires 25T thereof welded to the respective clips 41 and 42 as will be evident in FIGS. l and 3 of the drawings. Each of the clips has a terminal screw 42S whereby a line wire may be connected to the terminal clip.

rl`he other terminal clip 43 constitutes the common terminal for the two heating elements 25E as will be evident in FIG. 1 of the drawings, and the clip 43 is therefore connected to both of the terminal wires 25T of the vother short ends 26 of the heating elements 25E. Three line wires 69 are shown and each extends through a respective one of the openings 45 through the rear wall 'Ihe several terminal clips are located in the pockets of the terminal block 28, with the screws 42S thereof over clearance pockets 44 formed in the bottom wall 28B and the inner end of the bottom wall 28B of the terminal block is arranged to underlie and bear against the outer ends of the terminal portions 26 of the heating element.

'For holding the terminal block 28 on the outer ends of the terminal portions 26 and protecting the terminal block and terminal connections against grease and spillage, two inner end cover plates 48 of sheet metal are provided at the inner end of the terminal block and which conjointly extend substantially entirely across the inner end of the terminal block.

These plates 48 are alike, except as hereinafter noted, and one, which is identified by the reference character 48A, is secured to the outer ends of the short terminal portions 26 which lead from the outer coils respectively of the spiral windings of t-he two heating elements 25E and the other, which is indicated by the reference character 48B, is secured to the outer ends of the long terminal portions 26 which lead from the inner coils respectively of the spiral windings of the two heating elements 25E.

In the expansion and contraction of the heating elements under the changes of temper-ature to which they are subjected, the coils thereof tend to expand and contract and 'by reason thereof the terminal portions 26 at the opposite ends of each element 25E tend to move toward Iand away from one another and as the corresponding ends of eac-h heating element 25E tend to move Similarly in this manner the two short terminal portions 26 which are connected to the plate 48A tend to move similarly toward and away from the long terminal portions 26 which are connected to the plate 48B and thus by employing separate plates 48A and 48B expansion and contraction of the coils is accommodated and each element 25E is `free to expand and contract.

Moreover the pockets in which the terminal clips 41, 42 and 43 are located are of sufficiently greater width than the clips located therein so that these clips are free to move sidewise in their pockets to permit `freedom ofrexpansion and contraction of the coils of the elements 25E.

The plates 4S are located quite close to one another, substantially as shown in FIG. `l, when the heating elements 25E are a-t normal room temperature and separate to some ex-tent when the heating elements 25E are energized, and the terminal block 28 is attached to the ends of the terminal portions 26 and to the plates 48 in a manner to permit suc-h rel-ative movement of the plates 48 with respect to one another and corresponding movement of the ends of the terminal portions 26 which are attached to the plates.

Each plate 28 is correspondingly provided with top and bottom flanges 49 and 50 respectively between which the inner end of the terminal block isv interposed, as shown in FIGS. l, 2 and 3 and each lower flange 50 is formed with a spring latch portion 'SOR which resiliently engages in a recess or notch 128 provided therefor in the underside of the terminal block 28 and each recess 128 is of substantially greater width than the width of the latch member SGR engaged therein, as indicated by the dotted lines at 128 and SOR in FIG. 1, to permit sidewise movement of the latches 50K in the recesses 128.

These spring latches cause the bottom w-all 28B of the terminal block 28 to bear against the ends of the terminal portions 26- and against the protruding terminal Wires 25T, as shown in FIG. 3, so that the latches 50R are etective to hold the terminal block in position -at the outer sides of the plates 43 and when the terminal screws 42S are applied so that they project into the clearance pockets 44 they provide additional means for holding the temiinal block 28 in assembled relation on the plates 48. The top ange 49 of one of the plates 48 is provided with a threaded opening -therethrough for a screw 48S by which a ground Wire is connected to the heating uni-t and the screw 48S is located at the pocket which contains the common terminal clip 43 but at a place where it makes no contact with the exposed electrical conductors in the pocket.

The plates 4S are permanently secured to the respective pairs of terminal portions 26 in a manner to provide a se-aled connection which will preclude passage of grease or spillage therethrough, and for this purpose the terminal portions 26 pass through plate openings which have annular anges 48F projecting therefrom which are staked onto the sheaths of the terminal portions 26 or welded thereto to iixedly secure the plates 48 to the terminal portions 26 and provide a leak-proof connection.

By reason of the upward and outward inclination of the terminal portions 26 from the bends 26A thereof grease and spillage from the cooking operations drains from the tubular sheathed elements at the hinged end thereof to the lower extremity of the bends 26A and does not ow outwardly along the inclined portions 26 to the outer ends thereof and moreover, any spillage that may reach the outer end of said portions 26, as for example, when the heating unit is tilted to the upraised position, is prevented by the plates 48 from reaching the end extremities of the portions 48 and the conductors within the terminal block, as such spillage drains downwardly on the plates 48 to the bottom flanges 50 and drips off therefrom.

The mounting of the pivot pin 34 in the flange 23V surrounding the opening in which the heating unit is located is advantageous as it not only provides a positive pivoting of the heating unit so that it swings readily to the upraised position without inconvenient manipulation which is oftentimes required when a loose composite sliding and pivoting is employed, but it also avoids the long offset arms which are required when vthe heating unit is pivoted underneath the range top at a distance from the range top opening in which the heating unit is located.

Thus short straight -arms 24H may be employed for the hinging of the heating unit and the heating unit may be tilted to a highly upraised position affording ample access to the underside of the heating unit and to the interior of the mounting -ring and to the pan therein.

In this upward tilting of the heating unit all of the terminal portions 26 that are at or beyond the bends 61 swing inwardly toward .the center of the opening in the mounting ring, and the pan is notched at 25C to provide clearance therefor in the upward tilted position of the heating unit.

In order that thepan 29 may have a receptacle portion to retain spillage therein, it is important that the pan 29 is of a substantial depth and with a conical surrounding wall with a substantial inward and downward slope at the hinge side thereof, so that the bottom of the notch 29C is considerably closer to the center of the pan than the open upper end of the notch so that the latter does not extend to or Ithrough the bottom of the pan but leaves a substantial receptacle portion therebelow to accommodate spillage therein.

While I have shown and described my invention in a preferred form, I am aware -that various changes may be made therein without departing from the principles of the invention, the scope of which is to be determined by the appended claims.

What I claim is:

1. A tubular sheathed electrical resis-tance heater having tubular sheathed resistance containing coil portions distributively arranged to provide a iiat winding which is applicable to a range top for cooking thereon, said winding having a plurality of sheath end portions extending downwardly from the winding vat the underside thereof and providing terminal stems which project outwardly beyond the margin of the winding in side by side relation at approximately a common level and with terminal conductors projecting from the terminal stern ends, said terminal stem ends being contained within a one piece terminal block of electrical insulating material which is detachably secured to the stems and projects outwardly beyond the outer ends -thereof and is formed with a plurality of stalls extending outwardly along a side -wall of the terminal block, said stalls being open at their inner ends and having the outer end portions of the stems and their terminal conductors projecting into the stalls through the open ends thereof and extending outwardly in the stalls toward the outer end of the terminal :block for connection therein of current supply conductors to the terminal conductors for energization of the heater, the stalls being provided with entrances thereto at their outer ends for reception of current supply conductors therein for attachment -to the terminal conductors, and the stems having clamping means thereon between which and the ends of the stems and the projecting terminal conduct-ors an inner end portion of the said side wall is clamped for detachably securing the terminal block to the stems.

2. A tubular sheathed electrical resistance heater as defined in claim l in which the terminal conductors include wide portions at their outer ends and the stalls of the terminal block are of a width |from end to end thereof to accommodate the width of said wide portion of the terminal conductors therein.

3. A tubular sheathed electrical resistance heater as defined in claim l in which the clamping means comprises spring means which is mounted on the stems and engaged against the outer side of the first wall and resiliently clamps the outer end portions of the stems and their terminal conductors against the inner side of said wall.

4. A tubular sheathed electrical resistance heater as deiined in claim 1 in which said wall is stepped at the inner side thereof and the outer end portions of the stems and the terminal conductors overlie respective different elevational steps and said wall is engaged at the outer side thereof between said respective different elevational steps by said clamping means and the clamping means clamps the outer end portions of the stems and their terminal conductors against their respectively different elevational steps.

5. A tubular sheathed electrical resistance heater as defined in claim l in which the terminal bloei; is slidable endwise into latched attachment to the stems.

6. A tubular sheathed electrical resistance heater as defined in claim 1 in which an inner end portion of said wall is slid-able endwise between the outer end portions of the stems and a spring latch to a position of latched engagement therebetween by which the terminal block is attached -to the stems.

7. A tubular sheathed electrical resistance heater as delined in claim l in which an inner end portion of said wall is slidable endwise between the outer end portions of the stems and a spring latch to a position of releasable latched engagement therebetween by which the terminal block is attached to the stems, and the terminal conductors are provided with means by which current supply conductors are connectible to the terminal conductors and said means is operable -to lock the terminal block on the stems in said position of releasable latched engagement of the inner end portion of said wall between the outer end portions of the stems and the spring latch.

8. In a surface unit for the cooking top of electric stoves in which a spirally coiled sheath-type electric heating element having terminal wires extended from the ends of the sheath is supported on a mounting unit, the improvement that comprises a terminal block formed from insulating material and having a plurality of terminal pockets defined in part Iby a bottom wall and open at the top and at one end thereof, terminal clips connected to said terminal wires, separate protective plates fixed on and relatively close to the respective ends of said sheaths in a normal relation thereto, Ibottom flanges on the -lower edges of the respective plates in position to extend rbeneath said Ibottom wall when said terminal cli-ps are inserted endwise into the open ends of said terminal pockets, and cooperating means on said bottom anges and said |bottom wall yieldingly engageable in such insertion of said terminal clips to prevent withdrawal of such clips while allowing limited movement of said clips and said plates laterally of said pockets.

9. In a surface unit lfor the cooking top of electric stoves in which a spirally coiled sheath-type electric heating element having terminal wires extended from the ends of the sheath is supported on a mounting unit,

the improvement that `comprises a terminal block formed 'from insulating material and havingk a plurality of ter on the lower edges of said plates positioned to engage said locking recesses when said terminal clips are inserted into said pockets and to clamp said ends of said sheaths against said bottom wal-l and prevent inadvertent 5 withdrawal Iof the terminal clips from said pockets.

References Cited in the le of this patent UNITED STATES PATENTS Sharp Feb. 24, 1942 2,684,431 Cunningham July 20, 1954 

